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Old 01-01-2012, 09:21 PM   #1 (permalink)
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Default Misfiring and stumbling on acceleration

Hi I've been having consistent misfiring issues with my s800 (196). Gone through the whole ignition system....replaced all typical tune up parts, but there is still misfiring stumbling when it's throttled. So I've come to the dist. I think the point set plate is catching a bit and there seems to be some endplay.seems I need my distributor rebuilt. I know Michael Mayben rebuilds them. If I could get some info on the rebuilds that would be great!
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Old 01-02-2012, 06:35 AM   #2 (permalink)
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Default Re: Misfiring and stumbling on acceleration

after reading your post , IMHO, i would be looking at my fuel delivery. if the engine only misses upon acceleration and doesnt do it at idle or in cruise then chance are you have an accelerator pump acting up or trash in the system.
dizzy end play will cause trouble but mostly with timing.
maybe im wrong, but if you have gone through the entire ignition system, and it idles good and runs good at cruise, then your accel pump has got to be the issue.
i'm sure someone else will chime on this with some other ideas on where to look also!
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Old 01-13-2012, 10:05 PM   #3 (permalink)
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Default Re: Misfiring and stumbling on acceleration

Thanks for the info. I've gone through the carb, and I've removed and cleaned up the distributor. It idles well, it just seems to stumble at hard ecceleration. I've eliminated the fuel issue by hanging a new fuel can above the carb. I've set the dwell at 34, timed it to 5 before top dead. Adjusted the idle to 650 rpm.

I could really use some help here. I'm not an expert.
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Old 01-14-2012, 08:13 AM   #4 (permalink)
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Default Re: Misfiring and stumbling on acceleration

So while under constant throttle position and loaded it misses?

What coil are you running? What balast resistance are you running?

While it is missing can you see any exhaust discharge like dark smoke? If not, this is sounding a bunch like ignition and to be specific a coil or wires.

Remember that a spark jumping a gap (spark plug) while under higher cylinder pressure requires a larger voltage to jump the same gap. If you have a marginal coil or week spark due to a low coil supply voltage the engine can miss eraticly. Not a rythmic consistantly timed miss.

Is it at all possible to get a video or audio recording of the miss? It will go a long way to help pinpointing the source.

I have a test for you. Ignition on and volt meter connected to the + and - coil terminals and points closed (you can connect the - coil terminal to ground to get the same result.
What does the voltage read? Be quick with the test to avoid over heating the coil or ballast resister. Do all of your conecting with the key off and switch it on to read the voltage then turn it off. Your OK for a minute or two but that's all.
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Old 01-18-2012, 09:48 PM   #5 (permalink)
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Default Re: Misfiring and stumbling on acceleration

Ok, Robert, I got around to trying a few of your suggestions. I replaced the coil and wires. It starts up great, and runs smooth. It's just after five to ten minutes of run time, if you open up the throttle just a little, maybe 1200 to 1400 rpms it starts sputtering at that speed. At idle it's fine and it clears up at higher rpms. Oh yeah maybe at little hesitation when you dump the throttle. Now what do I look for? Thanks for any help you can give me.
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Old 01-18-2012, 10:50 PM   #6 (permalink)
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Default Re: Misfiring and stumbling on acceleration

I'm confused. Robert asked you a series of questions, but you didn't answer any of them. You say you ran some tests, but you didn't report any results. The observation about transition stumbling adds very little to the overall diagnostic picture. Maybe your coil and plug wires needed to be replaced and maybe not. His suggestion was to take a reading and post the results, not to replace parts.
Look, I know I'm dropping the hammer on you a bit, which usually isn't my way. You shouldn't take it personally. Consider it tough love, IHON style. The point is, he asked you all those questions for a reason. The answers are puzzle pieces that he and others can use to better understand just what the hell is going on under your hood. I suggest you go back, re-read his last post, and make an honest effort to respond to as many of those questions as you can. If you're not sure how to proceed or need more clarification about something, by all means, ask. We enjoy helping folks out, but folks must be willing to help us help them. Make sense?
Now I'm off to bed. I came off kinda cranky there.
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Old 01-19-2012, 06:22 AM   #7 (permalink)
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Default Re: Misfiring and stumbling on acceleration

Yep, I think "Cranky Sailor Jerry" summed it up for me.

The simple tests I asked for are a means to an end. Never once did I say Through parts at it.
Don't take this personaly but trouble shooting an issue from a distance is difficult as it is. The tests will narrow down the possible causes. I can't help any further unless the tests are run.
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